ok, i've worked around this by removing the old dest dir!
so each time I rsync it's in a brand new non-existing destination! thus any dest files that I wanted removed(because they're in exclude list) are going to not be there.
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I have to include the root dir /  in included files!
because, otherwise excluding files in excluded list has no effect! they won't be deleted even if I include the filename in both lists!

ie. if I want to ensure /etc/resolv.conf  is nolonger backed up, then
I have to include /etc/ in excluded list, else resolv.conf won't be removed from destination!

